The field of application servers has recently become one of the fastest-growing and most important fields in the computing industry. As web applications and other distributed applications have evolved into large-scale applications that demand more sophisticated computing services, specialized application servers have become necessary in order to provide a platform supporting these large-scale applications. Applications that run on application servers are constructed according to an n-tier architecture, in which presentation, business logic, and data access layers are kept separate. The application server space is sometimes referred to as “middleware”, since application servers are often responsible for deploying and running the business logic layer and for interacting with and integrating various enterprise-wide resources, such as web servers, databases, and backend or legacy systems. For example, an application server may act as a platform hub connecting web servers, database servers/services, e-commerce servers/services, backend or legacy systems, or any of various other types of systems or services. A key benefit of many application servers is that they not only provide this service/system integration, but also provide centralized administrative or management tools for performing various aspects of system and application administration.
Despite this offering, and the scalability and reliability of application servers, many application servers lack differentiated quality of service. Quality of service is referred to as a collective measure of the level of service provided to a customer.
Traditionally, quality of service has been used in internetworking switching/routing protocols and real-time media streaming, for example, and is characterized by basic performance criteria including availability (low downtime), error performance, response time and throughput, connection set-up time, and speed of fault detection and correction. This type of quality of service is established during Transmission Control Protocol (TCP) or upper layer connection negotiation and relies on intervening routers to honor the quality of service identifiers or hints, which are set in headers. These hints, however, are not application visible, and thus cannot be used to create a differentiated quality of service level or context in the application server space.
As a result, in the application server space, it is desirable to provide a differentiated quality of service that is propagated throughout all activities that a particular request generates. This type of differentiated quality of service in the application server space can allow for smarter and more satisfying services while providing an efficient means by which a provider of services can structure and manage fees for such services. Consider, for example, a brokerage firm who provides, over a network, services such as obtaining quotes, performing research, and trading securities on financial exchanges. Such a firm may create several service classes of preferred customers, such as Platinum, Gold, and Silver. These types of customers can thus enjoy superior and faster service of their requests based on their particular service class, the type of transaction desired, and the time constraint, if any, applicable to such request.